Quinolyl aliphatic alkylene polyamine poly acid



United States Patent QUINOLYL ALIPHATIC ALKYLENE POLYAMINE POLY ACIDFrederick C. Bersworth, Verona, N. L, assignor to The Dow ChemicalCompany, Midland, Mich, a corporzn tion of Delaware No Drawing.Application July 13, 1953,

Serial No. 367,722 1 8 Claims. (Cl. 260-287) This invention relates tochelating agents for metal ions in aqueous solutions and has for itsobject the pr0- vision of water-soluble aliphatic alkylene polyaminepoly acids and alkali metal salts and ammonium base salts thereof whichreact to form metal chelate compounds with metal ions in aqueoussolutions.

Another object is to provide quinolyl aliphatic alkylene polyaminepolyacetic acid compounds which are watersoluble and which formwater-soluble salts and chelate compounds.

Other objects will be apparent as the invention is more fullyhereinafter disclosed.

In accordance with these objects I have discovered that when one of theamino hydrogens of an aliphatic alkylene polyamine is displaced by aquinolyl group and the remaining amino hydrogens are displaced by aceticacid groups or by higher fatty acids, the quinolyl polyamino polyaceticacid, its alkali metal salts, ammonium salts, and amine salts, hasimproved chelate-forming properties, and forms stable water-solublechelates with a large number of mono and polyvalent metals than normallyformed by the alkylene polyamino polyacetic acid compounds in which allamino hydrogens have been displaced by acetic acid groups.

The compounds of the present invention fall generally under thefollowing structural formula: j

wherein R may be an acetic acid residue, a propionic acid residue orhigher fatty acid, the alkali metal salts thereof, ammonium salt thereofor amine salt thereof;.Alkylenerepresents bivalent alkyl radicalscontainingiZ to 4 carbon atoms arranged structurally in such a manner asto interpose at least 2 and not more than 3 carbon atoms between thenitrogen atoms; 11 is a positive integer and is selected from the groupconsisting of 1, 2, 3 and 4 and higher. Thus polyamine compounds such asdiethylenetriamine or dipropylenetriamine, having skeletalconfigurations characterized by the following:

--N--Alkylene -NAlkylene--NAlkylene+ are formed.

In this group of compounds I have found that the ethylene diaminepolyacetic acid series of compounds are the most stable" andeconomically practical series of compounds and the invention will bedescribed as it has been adapted to the manufacture of this series ofcompounds primarily. In this series of compounds very stable chelatecompounds are formed with a large. number of metals, such as Mg, Be, andFe which are not formed readily with the ethylenediamine tetraaceticacid.

2,751,386 Patented June 19, 1956 Somewhat less stable chelates areformed with Ca, La Fe Zn Cd In the case of Cu it was found that thechelate, while quite stable, is not nearly as stable as the copperchelates formed with other chelating agents, such asethylenediamine-N,N'-diacetic acid and B, B, B" triamino triethylamine.

in the case of the bivalent transition metals the situation is somewhatcomplicated by the formation of two types of chelates, in which theratios of the S-quinoline amino acid to metal are 1:1 and 2:1. The 1:1chelates are rather more stable than those of ammonia triacetic acid,which has been described in considerable detail in the literature. Thecorresponding chelates of the alkaline earth and rare earth metals (withthe exception possibly of Mg and Be) are much less stable than those ofammonia triacetic acid. The 2:1 chelates for the transition metals areextremely stable and in neutral solutions even at very lowconcentrations (10 to 10- molar) the degree of dissociation of thecheiate is so low that it cannot be measured.

When n=1, the 1:1 chelates with all metals are much more water solubleand much more stable than the 1:1 chelates formed when 11:0.

Furthermore, with transition metals such as Co, Ni and Cu the chelatesare much more stable than those formed with the very powerful chelatingagent ethylenediamine tetraacetic acid. With alkaline earth and rareearth metals, however, the chelates are less stable than those ofethylenediamine tetraacetic acid. Increasing the chain length (i. e. forhigher values of It) increases the number of metal ionssequestered permole of chelating agents. Thus when n=3, the one mole of compoundsequesters two moles of heavy metals. The stability of these chelates issomewhat less (i. e. the degree of dissociation is slightly higher), butis still sufficiently great to completely deactivate metal ions.

In the following examples illustrating the syntheses of compoundsbelonging to this family of chelating agents, it is noted that thecompound is synthesized as its alkali metal salt in a strongly alkalinemedium. Subsequently it is isolated in acid form by taking advantage ofthe fact that symmetry of the compound renders it relatively in: solublein water and, the synthesis having been completed, the acid form isprecipitated by acidifying the reaction medium in which it hasbeenformed. The corresponding alkali metal salts, ammonium salts and aminesalts are then formed pure by reacting the acid with the hydroxide orcarbonate of the alkali metal or ammonium base and drying the resultantsolution. In this fashion, sodium, potassium, lithium, rubidium, cesium,ammonium and amine salts of the compounds may be formed. crude alkalimetal salt can be recovered from the reaction medium itself directly byevaporating to dryness without acidification. However, the grade ofcompound recoverable then is dependent upon controlling the reaction sothat substantially equimolar amounts are reacted thereby to leave behindinsignificant residues of reactant.

Example I 0 moles of NaCN and three moles of formaldehyde (by theprocess described in my U. S, Patent No. 2,407,645). The product may beobtained as a crystalline substance 1,}? from the aqueous solutionstrongly acidified with HCl, and is believed to have the followingformula:

This acid form of the compound is readily converted to the alkali metalsalt by reacting it with enough of the corresponding alkali metalhydroxide or carbonate, ammonium hydroxide or amine in aqueous medium toneutralize it, and then recrystallizing the compound. Partialneutralization just removes the HCl from the molecule to form the freeacid. Further partial neutralization will give acid salts.

In this and succeeding examples, use of a diamine having a substitutealkylene nucleus will give a comparable compound. For example,isopropylene diamine, NI-l2CH(CH3)CH2NHz could be used for ethylenediamine.

Example II One mole of 8-aminoquinoline was agitated with one liter ofwater and heated to the reflux point and vigorously stirred while anaqueous solution of one mole of B-chloroethylamine-N,N-diacetic acid wasslowly added over a period of two hours. The reaction mixture was thenheated and stirred for two hours more and then brought to a pH of withcaustic soda solution. The intermediateethylenediamine-N-quinolyl-N,N-diacetic acid, was then reacted(according to the process described in my U. S. Patent No. 2,407,645)with one mole of NaCN and one mole of CI-IzO. The reaction product, onacidification with excess hydrochloric acid yielded a crystallinematerial believed to have the formula:

Example III OHrCOOH One mole of S-bromoquinoline is treated by themethod of Example I with the exception that diethylenetriamine is usedin place of ethylenediamine and the intermediate amine is treated with 4moles of sodium cyanide and 4 moles of formaldehyde. The final productis believed to have the formula:

The alkali metal salt can be formed by reacting equimolar amounts ofcorresponding alkali metal hydroxidc or carbonate, ammonium hydroxide oramine in aqueous medium and then recrystallizing the compound. Partialneutralization just removes the HCl from the molecule to formtheireeacid. Further partial neutralization will give acid salts.

Example IV One mole of 8-bromoquinoline is reacted according to theprocess outlined in Example I, with the exception A that trimethylenediamine is used in place of ethylenediamine. The final product has theformula:

The alkali metal salt can be formed by reacting equimolar amounts ofcorresponding alkali metal hydroxide or carbonate, ammonium hydroxide oramine in aqueous medium and then recrystallizing the compound. Partialneutralization just removes the HCl from the molecule to form the freeacid. Further partial neutralization will give acid salts.

Example V In the fashion demonstrated for Examples I-IV,dimethylenetriamine, triethylenetetramine, tetraethylenepentamine andhigher alkylenepolyamines are used to prepare other quinolylderivatives.

It is to be noted from the several examples that the acid form of thecompound, its partial salt or completely neutral salt may be prepared.To form the fully neutral salt sufficient alkali (whether alkali metalbase or ammonium base) must be used to neutralize all of the acidfunctions of the compound. In Examples I and II three acetic functionsappear. Hence, to form the neutral salt, the hydrochloric acid wouldfirst be neutralized and three additional moles of base would be needed,for a total of four moles of base. In Example III five moles of basewould be needed for the neutral salt; four moles in Example IV. InExample V, each alkyl amino group in the polyamine chain would add anacid function to the compound. The preparation of the salts is carriedout as a common acid-base titration and inflections in the acid-basetitration curve identify the formation of the mono-, di-, trietc. saltsof the compounds. Isolation of the salts calls merely forrecrystallization.

As an example of the reactions of these chelating agents which causedeactivation of metal ions, the interaction of the compound of Example Iwith Ca and Co are given:

Ca i-quinolyl ethylenediamine triacetic acid In carrying out the abovereaction, the calcium ion and the acid ion of the quinolylethylenediamine triacetic acid are visualized as forming the chelate setforth. In practice, the calcium ion would be present in the solution aschloride or acetate, for example, and the quinolyl chelating agent wouldbe used in the form of its sodium salt, which is the most common formfor application. Similarly, with respect to the following reactionshowing the formation of cobalt chelate, the cobalt can be present insolution as either the chloride or nitrate and the sodium salt of thechelating agent would be used:

Co +quinolyl ethylenediamine triacetic acid- Thus it is seen that sixactive groups are available for chelation with metals using the simplermembers of the family of chelating agents herein disclosed, but all ofthese groups are not necessarily used in every case. In similar fashionas the value of n increases, additional acid groups become available forchelation of heavy metal ions. Thus, formulating it generally thecompound may be stated as follows:

The higher polyalkylene polyamine derivatives are capable of bindingmore than one mole of metal per mole of amino acid. For example, thebinary compound formed between Cu and N-quinolyl triethylenetetraamine-N,N, N, N', N' pentaacetic acid is visualized as:

wherein Alkylene is a lower molecular weight group which places 2-3carbon atoms in the chain directly between the indicated nitrogen atoms,R is selected from the group consisting of -CH2.COOH and CH2CH2COOH;

n is a positive integer having a value in the range from at least 1 toabout 4; and the alkali metal, ammonium base and acid addition salts ofthe said compounds.

2. Compounds in accordance with claim 1, in which alkylene is -CH2.CH2-.

3. Compounds in accordance with claim 1, in which alkylene isCH2.CH2.CH2.

4. Compound corresponding to the following formula:

CHQ'OOOH 5. Compounds corresponding to the following OHz-COOH OHz-COOHCHz-COOH 6. Compound corresponding to the following (iJHz-OOOH CHZ'COOHNCH2'CHz-CH2N 0 H2 C 0 0 H N 7. Compound corresponding to the followingoHzoooNa CH COONa N 0 H2 0 Hz-N 0 H20 0 0 Na 8. Compound correspondingto the following

1. A COMPOUND WHICH IS A MEMBER OF THE GROUP CONSISTING OF COMPOUNDSCONFORMING TO THE FOLLOWING STRUCTURAL FORMULA